Gary Lunsford, the general curator at the zoo, has three choices: pair tigers to breed; give the females birth control; or spay/neuter the tigers like house cats.

The goal is to control the population of a captive species and ensure it stays genetically diverse.

"Breeding tigers in captivity is helping to sustain the captive populations so that... it’s not straining on wild populations," said Lunsford.

It’s not just tigers — the Assiniboine Park Zoo participates in 58 breeding programs, with species varying from insects to polar bears. The alternative, letting animals breed at will and then euthanizing the overpopulated captive species, is what caused an international controversy at the Copenhagen Zoo in Denmark this year.

In February, Copenhagen workers shot a healthy giraffe named Marius in the head, dissected his body and publicly fed him to the lions. Zoo officials told media they killed the animal to prevent inbreeding because there were already many giraffes in the breeding program with similar genes. About a month later, zoo workers killed two young lions and two older lions to make way for a new male that was brought in from another Denmark zoo. A spokesman told media the new lion would have killed the two young lions.

To control the population of Siberian (Amur) tigers at the Winnipeg zoo this year, a vet put the females on birth control, administered either as an annual injection or a slow-release implant under the skin.

"We generally try to train them so that they will accept the injection voluntarily," he said. "If they’re not trained to do it, we just wait until we have the opportunity, like when we’re doing an exam."

When contraceptives aren’t used, some animals are separated into different cages during their mating season.

"The reindeer, the muskox, the markhor, they all cycle seasonally, so as long as they’re not together during the breeding season, they can be together for the rest of the year — same with polar bears and lynx," he said. "As a general rule, tropical species tend to be non-seasonal in their cycles whereas animals in climates like this have to be seasonal in their cycles or they would have babies born at the wrong time of the year."

There is also a larger family tree to consider. Most breeding programs involving the Assiniboine Park Zoo are run by the Association of Zoos and Aquariums (AZA) in the United States. The association lists each animal in its breeding programs in comprehensive databases — called "studbooks" — that have information about the animal’s pedigree and demographic history. This information helps determine the population status and genetic diversity of a species. In other words, it answers the question, "to breed or not to breed?"

That answer can change from year to year, depending on the genetic diversity of the species, whether it’s endangered, and whether zoos have room for more animals.

For example, the Assiniboine Park Zoo bred the same pair of lynx for three years. After 14 cubs, the zoo halted their breeding.

"You can very easily get too many of those same genetics in the populations where it’s no longer practical to reproduce that pair," Lunsford said.

Once the zoo stops breeding the animals, AZA has a transfer program that will determine the best place for the animals to go next. Sometimes that means sending animals to the other side of the world, which is what happened with a red panda at the Assiniboine Park Zoo.

"One of our females that was at another facility was sent over to Japan and they’re sending us one of their females from Japan just to maintain that genetic diversity," Lunsford said.

Even though these breeding programs are tightly managed, some think the answer to the question "to breed or not to breed?" should always be "no."

Rob Laidlaw is a co-founder and executive director of Zoocheck Inc., a national animal-protection charity based in Toronto. He’s all for zoos using contraceptives.

"If we can do anything to stop the production of any unwanted animals, we’re in favour in that," said the specialist in captive-wildlife issues. "There’s a large number of common animals that are being produced, and a lot of them are in surplus."

He said his organization has been trying to change the "zoo paradigm" — the priorities of the zoo — for years.

"The totem pole of priorities is the public first, staff second and animals third."

Laidlaw wants to flip that around so the animals are first and the public is last.

"(Zoos) would be far more humane, there would be fewer animals and they would fulfil a purpose that zoos say they do now but don’t."

The stated purposes of breeding programs are misleading, he said.

"They imply that they’re replenishing the wild with the animals that they’re breeding," he said. "They’re breeding animals to replenish zoo displays."

"If they said ‘we’re here to entertain,’ I’d be OK with that."

The Assiniboine Park Zoo has its own European reindeer breeding program that has operated for years. But Lunsford said the zoo will "certainly not" release this stable species back into the wild.

"We’ve had so many facilities asking us for reindeer that we continue to reproduce our reindeer," he said. "When other facilities stop asking for them, we’ll stop breeding them."

The Assiniboine Park Zoo is also part of an AZA green squirrel monkey breeding program and breeds a subspecies of squirrel monkey that’s not endangered, the saimiri sciureus. "There are other subspecies that are more in peril than the subspecies we have, but there’s not enough of them in captivity to create a breeding program," Lunsford said.

He said breeding programs don’t necessarily reflect the level of threat to a certain species.

"Sometimes, endangered species are harder to create a breeding program for because they’re endangered species — the fewer numbers, the harder it is to maintain genetic diversity, which means the harder it is to create a sustainable captive population."

So if not for the purpose of saving an endangered species, why have a breeding program?

"Common species are essential for connecting people to nature, conservation messaging, education and/or research, and it is just as important to oversee their population health through co-operative management."

Laidlaw, the Zoocheck critic of breeding programs, disagrees.

"There’s no need to breed them. There’s no opportunity for releasing animals into the wild."

He’s also skeptical of zoos that participate in common reintroduction programs, including burrowing owls and black footed ferrets, saying "they try to hide behind this facade of conservation."

The Assiniboine Park Zoo participates in the breeding and reintroduction of burrowing owls, which are native to Canada.

Laidlaw argues these reintroduction programs would be better-handled by other organizations.

"It could be somebody with some funding, it could be a volunteer group that doesn’t need the zoo."

But Dorsey counters the international AZA pro-breeding group supports conservation efforts.

"AZA-accredited zoos/aquariums contribute $160 million each year to more than 2,700 field-conservation projects in more than 100 countries — making AZA-accredited zoos/aquariums true conservation centres working to preserve these species in nature."

Lunsford said the burrowing-owl program is the zoo’s most successful breeding operation.

"That’s an easy program for us to be involved with because we can work with Manitoba Conservation to reproduce and release. That’s the most practical program for an endangered species."

The only other species that’s part of a breeding program at the Assiniboine Park Zoo that Lunsford knows has been released back into the wild is the silvery gibbon, a primate from Indonesia.

Meanwhile, zoos around the world continue killing some of their surplus animals — to the outrage of many people.

Despite a petition to stop Copenhagen Zoo workers from killing Marius that garnered more than 25,000 signatures, the six-month-old giraffe was shot Feb. 9.

After the incident, a spokesman for the European Association of Zoos and Aquaria told media the association supports the zoo’s decision and said on average, a zoo in its membership kills about five large mammals annually.

With 347 zoos in its membership, that’s a total of 1,735 large mammals killed each year.

"When our members do make the difficult decision to euthanize an animal, it is most often for the health and welfare of the animal, which can include old age, and to prevent the spread of disease."

Lunsford said the Assiniboine Park Zoo doesn’t euthanize animals, but he understands why the Copenhagen Zoo did what it did.

"Generally those decisions are made based on the quality of life for the animal."

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Is she, or isn't she?

Since breeding programs are so tightly regulated, zoos need to know whether or not an animal is pregnant to make room for the babies and better control the genetic diversity of a species. These are just some of the ways zoos conduct pregnancy tests.

● Some primates are so closely related to humans they can use over-the-counter pregnancy tests. Pregnancy tests are designed to recognize and bind human chorionic gonadotropin (hCG), a hormone produced during pregnancy. These tests are more likely to be accurate for chimpanzees, gorillas and bonobos because they’re closely related to humans. The more distantly related a species is from humans, the less likely the test is to be accurate on non-human primates.The Assiniboine Park Zoo gives its animals pregnancy tests by collecting their feces over time to test for fluctuations in hormones. A key hormone to indicate whether or not an animal is pregnant is the steroid hormone; females produce higher levels of this hormone when they’re pregnant. This pregnancy test is non-invasive for the animals and zoo staff doesn’t have to handle the animals.

● A two-year-old beagle’s nose is about as accurate as an over-the-counter pregnancy test. Scientists at the Cincinnati Zoo’s Center for Conservation & Research of Endangered Wildlife (CREW) tested to see if a dog named Elvis could distinguish a pregnant polar bear from a non-pregnant bear by smelling fecal samples last year. Elvis was 97 per cent accurate. He was trained to pause and sit when he detects a pregnancy and to not show interest in samples from non-pregnant bears. After his training, Elvis was put to the test in October 2013. He was given 34 samples of feces to sniff from the 17 potentially pregnant polar bears that mated in the spring. The zoos that participated in this study were then told whether or not Elvis suspected their polar bears were pregnant. This study is meant to help zoos determine whether or not they should mimic wild conditions for pregnant polar bears in the winter. In the wild, pregnant polar bears enter dens and don’t eat or drink for months. Non-pregnant bears spend the winter outside of dens. Zoos want to isolate the pregnant bears with little disruption and film them to know when babies are born and let non-pregnant females enjoy winter by swimming and socializing while out on exhibit with the other bears. This sniffer-dog project is still in the testing phase.

● Zoos can administer birth control through an injection or by slipping an implant under the animal’s skin. Zoo staff will often train the animals, such as Siberian tigers, to accept the injection. Some zoos, including the Assiniboine Park Zoo, use positive reinforcement to train their tigers. For example, zoos get their tigers to stand up on cue by blowing a whistle that signifies “good boy.” Trainers will then give the tigers food when the tigers do something they like. After a while, tigers associate the whistle with food. Once tigers know that, trainers hold an object up high and tigers stand up to put their nose to it to smell it. As soon as the tiger does this, trainers blow the whistle. Soon the tigers learn that every time the object goes up, they need to put their nose to it. Zoos often train tigers to stand up to check if they’re sick by looking at their paws and the pads of their feet.

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